96 Flora of the Palouse Region 



ate; leaflets ovate, mostly acute, rounded or cordate at base, doubly and 

 somewhat incisely dentate, pubescent especially beneath, 2-5 cm. long: 

 calyx glandular and prickly: petals white, about as long as the acute some- 

 what foliaceous tip of the sepals: fruit black when ripe, cylindrical, 1-3 cm. 

 long, finely flavored. Thatuna Hills, in open woods, rare. 



155. AIXHEMILLA. 



Low annual or perennial herbs: leaves palmately lobed or com- 

 pound, with sheathing stipules: flowers perfect, small, greenish, in 

 corymbs: calyx 4-5-lobed, with as man}- minute bractlets: petals 

 none: stamens 1-4, very small: styles basal or lateral: carpels 1-4, 

 distinct, free from the calyx-tube: akenes 1-4, enclosed in the 

 calyx-tube. 



A. arvensis var. occidentalis Piper, n. comb. (A. Gtridentalis Nvl\X.) An- 

 nual, 2-8 cm. high, simple or branched below, sparsely hairy: leaves short- 

 petioled, fan-shaped, 3-parted, the lobes acutely 2-3-eleft; stipules conspicu- 

 ous, cleft: calyx 1-1.5 mm. long, acutely 4-cleft, the bractlets minute: akenes 

 ovate, pale, 1 mm. long. Stony soil, not rare. 



156. POTERIUM. 



Mostly perennial herbs: leaves alternate, odd-pinnate; stipules 

 adherent to the petiole: flowers small, often polygamous or dioe- 

 cious, in dense terminal spikes or heads: calyx 4-lobed. petal-like: 

 petals none: stamens 4-many: styles terminal, filiform; carpels 

 1-3, free from the calyx-tube: akenes usually 1, enclosed in the 

 4-angled dry closed calyx-tube. 



P. anniuim Nutt. Annual, erect, glabrous, 15-40 cm. high, usually 

 simple below: leaflets 4-6 pairs, 1-2 cm. long, ovate or oblong, deeply pin- 

 natifid into linear obtusish lobes: flowers perfect, greenish, in oblong spikes, 

 1-3 cm. long: bracts ovate, scarious-margined, persistent: calyx-lobes 

 broadly ovate, scarious: stamens 4, rarely 2, somewhat exserted. Dry 

 ground, common. 



157. GEUM. 



Perennial herbs: leaves pinnate, with stipules; radical clustered; 

 cauline smaller: flowers rather large, solitary or in corymbs: calyx 

 5-lobed with 5 alternate bractlets: petals 5, obovate, longer than 

 the calyx-lobes: stamens man}', on the throat of the calyx: styles 

 terminal, elongated in fruit, usually plumose or jointed: akenes 

 2-6, pubescent. 



Styles naked, jointed and bent near the middle: sepals reflexed. 



G. MACROPHVUVM. 



Styles plumose, becoming elongated: sepals not reflexed. 



G. TRIFLORUM. 



G. macrophyllum Willd. Stout, erect, 30-80 cm. high, bristly-hairy: 

 radical leaves pinnate, the terminal leaflet much larger than the 3-8 lateral 

 ones, broadly ovate, 3-7-lobed, dentate, 5-10 cm. long; lateral leaflets ovate 



